The invention relates to a method for optical chassis measurement of motor vehicles by means of a measuring arrangement equipped with at least one measuring device, in which one or more image capturing devices, which are associated with one another in terms of their position and location and record the surface geometry of a vehicle or measurement points arranged on the vehicle, carry out a referencing and/or orientation of the at least one measuring device in relation to the measuring station with the aid of reference features that are arranged at particular measuring station coordinates in the measuring station and, based on orientation data and/or association data obtained and based on measurement data obtained during execution of the axle measurement, an evaluation is carried out in an evaluation unit in order to ascertain chassis data; the invention also relates to an apparatus for carrying out the method.
A method and apparatus of this kind are disclosed in DE 197 57 763 and also in EP 1 042 643 B1. With these known methods and apparatuses, the axis of travel and geometrical data regarding the wheel and axle are determined with the aid of cameras, a reference coordinate system in the measuring station and optical features (for example retroreflective marks) on the vehicle wheel and chassis. According to DE 197 57 763, the measurement is carried out when the vehicle is at rest, e.g. over a workshop pit or on a car lift, while EP 1 042 643 B1 describes a method in which the vehicle is driven past the measuring device. Both methods simultaneously record the vehicle and a reference feature arrangement, which is equipped with a number of reference features, in order to reference and/or orient the measuring device of the system in relation to the measuring station.
Due to the ever greater technical improvements to chassis designs, determining the wheel and axle geometry of vehicles with a high degree of precision is becoming more and more important. New and more finely tuned possibilities for adjusting the track and camber of individual wheels require a measuring device that functions with a correspondingly high degree of precision. The referencing and orienting of the measuring device in relation to the measuring station are therefore of vital importance.
The (unpublished) German patent application DE 10 2005 063 051, in which even more methods and apparatuses according to the prior part are cited, discloses possibilities for the embodiment and use of the referencing by means of a reference mark arrangement during the chassis measurement.
The reference applications cited above include the requirement that the 3D coordinates of the reference features in a shared coordinate system, i.e. the measuring station system, must be known to the evaluation unit. No indication is given, however, as to how the coordinates are determined.